Chapter 4 Implants and anesthesia
Professor of Orofacial Pain Management Section, Graduate School of Medical and Dental
Sciences, Tokyo Medical and Dental University
Masahiko Shimada
I. Local anesthesia
Details of local anesthesia for implants are mentioned in the clinical practice edition, “Implantation
techniques for the AQB implant”, therefore, the characteristics of local anesthesia, local anesthetics andvasoconstrictors, and the effects of local anesthetics and their complications will be mentioned in thissection.

A. Characteristics of local anesthesia used in the dental field
The local anesthetics used in the dental field are required to reach and effectively numb the hard tissues(bones and teeth) after administration at soft tissue sites, through the pores in the bone. Therefore, themajority of uses of anesthetics in dental practice involve actions on hard tissues, in contrast to othermedical practice. Consequently, the properties that characterize the anesthetic medicines used in dental
practice are: use of high concentrations of local anesthetics, and the concomitant use of highconcentration of vasoconstrictors in order to maximize the anesthetic effects and stop bleeding. There is asignificant number of pain points present intra-orally. The anxiety and uneasiness that patients havetowards dental treatment, coupled with the discomfort and pain of the needle used for the induction of
local anesthesia, can trigger systemic accidental complications such as neurogenic shock andhyperventilation. Therefore, the local anesthetics used for pain management in implant treatments areoften administered together with topical and conduction anesthetic agents, or psychosedative agents, toprevent the onset of accidental complications.

B. Local anesthetics and vasoconstrictors
1. Dental local anesthetic
The local anesthetic agents that are used in the field of dental surgery are listed in Table 3-4-1. (Fordetails of pharmacological effects of each local anesthetic agent, refer to Chapter 5. Implant-related
medicines, or the Clinical Edition).

Brand name
Xylocaine cartridgefor dental use

Local anesthetic
Lidocaine hydrochloride

Concentration Vasoconstrictor
Adrenalin2%
1/80,000(0 0125mg/ml)
Hydrogen tartaric
2%acid adrenalin
1/73,000

Ora cartridge

Lidocaine hydrochloride

Citanest cartridgefor dental use

Propitocaine hydrochloride

3%

Propitocaine hydrochloride

3%

Mepivacaine hydrochloride

3%

Citanest-octapressin
cartridge for dental use
Scandonest cartridge

Hydrogen tartaricacid adrenalin
1/300,000
Felypressin
0.03IUNA

Measure1.8 ml
1.8 ml
1.0 ml

1.8 ml
1.8 ml
1.8 mlTable 3-4-1 Main dental local anesthetic agents12. Vasoconstrictors
The local anesthetic agents used for implant surgery are often combined with vasoconstricting agents,
taking into account the anesthetic effect, the duration of surgery, and the need to stop bleeding. The
common vasoconstricting agents currently in use are adrenaline and felypressin.
a. Pharmacological effects
The main pharmacological effect of adrenaline is peripheral vasoconstriction and an increase in heart
rate and stroke volume, with significant central nervous system effects, and in particular an increase in
myocardial oxygen consumption. Felypressin has a lesser vasoconstricting effect in comparison toadrenaline, but administration of large doses has been reported to result in coronary artery constriction
and diminished blood flow 1) 2).
b. Contraindications
The contraindications to adrenaline can be divided into absolute and relative contraindications; in thelatter case, it can be used under some circumstances. Adrenaline is absolutely contraindicated in patientswith hypertrophic cardiomyopathy and uncontrolled hyperthyroidism. If these conditions are wellcontrolled under the supervision of an internist, vital signs can be monitored, and if a reduced amountwill be effective, these subjects can be regarded as having a relative contraindication. Other relative
contraindications include high blood pressure, diabetes, ischemic heart disease, hyperthyroidism andarteriosclerosis. In addition patients who are regularly taking β-blockers, tricyclic and tetracyclic
antidepressants, and digoxin are also considered to fall into the conditional category.
The local anesthetic formulations of adrenaline typically contain 12.5 µg/ml. Taking this fact into
consideration, at least one cartridge (1.8 ml) may be adequate. Up to two of these cartridges can beadministered even in the presence of moderate circulatory disease (a relative contraindication) 3).
Relative contraindications to felypressin include ischemic heart disease and coronary arteriosclerosis,
and old age; the reasoning is obvious from the effect this agent has on coronary blood flow. If these
conditions can be well controlled, up to three cartridges can be administered. The implant treatments
often involve replacement of a number of teeth therefore it is essential to adhere to the dosages listed for
effective pain management.

C. Anesthetic effects 4)
1. Anatomical factors
When administering local anesthetic in the region of the mandibular molars, because the bone in thisarea is compact, and has few pores; it may be necessary to administer conduction anesthesia into themandibular foramen or into the papillary or peridontal space. In the case of implant surgery, concomitant
use of conduction anesthesia is recommended.
2. Inflammation
Where acute inflammation is present, lactic acid accumulates in this area, making the environment acidic.
This causes difficulty in producing free basic groups that pass through the neurilemma, thereby reducing
anesthetic effects. Improved anesthetic effects can be gained by the concomitant use of conduction
anesthesia, but for implant surgery, it is recommended that one waits for the acute inflammation to
subside before surgery is performed.
2Moreover, if the tissue has local chronic inflammation, the conditions resulting from formation of
granulation tissues such as hyperplasia of nerves, reactive densification of bone and increases in bloodflow act to weaken the anesthetic effect 4).
3. Psychological factors
In cases where there is extreme mental tension or anxiety towards a dental treatment or where thepatient is in poor physical condition, his/her pain tolerance is often impaired. Furthermore, if the patient
has preconceptions about his/her reaction to treatment, for example that anesthetics do not work properlyon them, or are ineffective, this can adversely affect the outcome of local anesthetic use. If this becomesthe problem, psychosedation can be administered concomitantly, as described below.
4. Dose administered
A sufficient dose should be administered, as too little can be ineffective in providing an anesthetic effect.
5. Speed of injection
If the injection speed is too fast, the local anesthetic drug can disperse from the point of introduction,
thereby reducing its action at the desired site.
6. Timing
If the surgical procedure is started before enough time is given after the injection of local anesthesia, thepatient will feel the painful stimulus as the anesthetic agent has not yet started to work. Even if
sufficient time has passed, and the pain threshold has become raised, not only the sense of pain, but alsopressure sensation and touch may act together to produce a painful sensation. Therefore, it is essential todefer surgery until sufficient anesthetic action has been achieved, which usually takes five minutes.
7. Site of injection
It is imperative to limit the number of injection sites to a minimum, to avoid leakages of the anesthetic
drugs from these sites, as this results in the efficacy of these agents being reduced.

D. Complications and how these are addressed 5)
Accidental occurrences before, during and after surgery are mentioned in the chapter “Accidental diseaseand complications”; therefore, in this chapter, we will only talk about the main local complications that
can arise from use of local anesthesia.
1. Accidental swallowing of the injection needle, and its entry into the trachea
Poor attachment of the needle to the local anesthetic delivery device at the time of anesthesia or inparticular, application of pressure while infiltrating local anesthetic, can result in the needle entering theoral cavity. This is problematic, especially in the elderly where the gag reflex is less efficient, and may
result in swallowing of the needle or its entry into the trachea.
a. Management
Stop the procedure, and let the patient cough to eject the injection needle. Confirm the presence of theneedle, and remove using needle forceps, Péan forceps, or artery forceps. If the needle cannot be removed,
the patient should be referred to a specialist medical organization.
b. Preventative measures
Take great care to lock the injection needle. Before intra-oral injection, test outside the oral cavity toensure smooth exit of the drug, and determine that the needle does not shoot off upon application ofpressure.
3

2. Needle breakage, and deviation
Generally, this can occur as a result of re-usage of needles, use of unsuitable needles, and misjudgment of
the depth, direction or site of injection. Further, deviation of needles in the tissues can occur as a result of
placing the needle deeply, upon which breakage of the needle within the tissues can occur, particularly ifthere is any change in the direction of the needle, whether this is due to movement of the needle by theoperator or the patient moves his/her face. This complication is most prevalent with delivery of
conduction anesthesia to the mandibular foramen.
a. Management
Use a mouth opener to ensure that the mouth remains open. Firmly grip, and remove the needle usingneedle forceps, Péan, or artery forceps. Avoid the use of tweezers as they do not grip effectively. If theneedle cannot be removed, the patient should be referred to a specialist medical organization (e.g.,dental/oral surgery department of a general hospital).
b. Preventative measures
Use new injection needles. Use needles of a designated thickness and length. Examine the needle before
use. Do not bend the needle before use. Do not insert the needle into its base. Do not change the directionof the needle once injection has started. The direction of the needle should be altered only once it has beenpulled back to the level of the submucosal membranes before proceeding. Hold the injection body in aposition where a rapid response to any sudden changes in patient’s facial expression or body movement ispossible.
3. Facial paralysis
Occurs either as a result of misjudgment in the direction or the position of insertion of the needle, or due
to the administration of an excessive dose. Common symptoms that manifest are inability to close the eye,loss of the nasolabial sulcus, inability to whistle and sagging of the angulus oris.
a. Management
Clearly explain what has happened to the patient, protect the eye with an eye-patch if the eye cannot
close, and refer to a specialist organization.
b. Preventative measures
Administer the correct dosage of anesthesia, direct the needle accurately, and insert the needle correctly.
4. Trismus
This can arise as a result of damage to or infection within the soft or hard tissues, arising from theinjection needle during the administration of conduction anesthesia at the mandibular foramen. In thecase of infection, onset occurs around 24 hours, with symptoms reaching a maximum within 72 hours
from the time of induction. Regarding muscular damage or internal bleeding without infection, pain
occurs at the time of insertion or on mouth opening, and the symptoms will show improvement after a few
days to a week.
a. Management
Administer antibiotics early on
b. Preventative measures
Disinfect the oral cavity sufficiently before the procedure, and take great care in determining the4direction and the depth of injection.
5. Internal bleeding, hematoma, and swelling
These commonly occur as a result of damage to blood vessels or a venous plexus by the injection needle,
and in particular, in patients with a hemorrhagic diathesis or those who are currently taking
anticoagulants. The internal bleeding from infiltration anesthesia spreads from the submucosal layer tothe subcutaneous tissues and into muscular tissues, resulting in purpura.
a. Management
Perform pressure hemostasis and give antibacterial agents to prevent infection.
b. Preventative measures
Take great care in determining the direction and the depth of injection. In addition, test whether there isany back-flow of blood before injecting liquid medicines. Pay particular attention to patients who sufferfrom a hemorrhagic diathesis and those taking anticoagulants.
6. Sensory paralysis
Caused by nerve injuries, hematoma and nerve compression from the injection needle. Sensory paralysis
may occur along the direction of nerve flow from 24 hours to a few weeks after injection. The symptoms
can persist for up to few months.
a. Management
On inducing conduction anesthesia at the mandibular foramen, it is imperative to identify the nerve thatis to be anesthetized, between the inferior alveolar and the lingual nerve. Explain to the patients in detailthe aftercare, and that the recovery period is largely dependent on the extent of the nerve damage. It cantake from a few months to over a year, and, where necessary, a specialist in the field will need to be
consulted.
b. Preventative measures
Take great care in determining the direction and the depth of injection, as well as identifying factors that
could lead to infection or bleeding.
7. Local ulcers, necrosis and stomatitis
Factors such as an overdose of local anesthetics and exertion of excess pressure at the point of injection
can result in these conditions. Additionally, the use of expired local anesthetics, or the administration ofhigh concentrations of vasoconstrictors or local anesthetics can be the cause. These can occur particularly
when injecting into the interdental papilla or the palatal mucosa. Symptoms such as redness and pain at
the injection site can occur within 24 hours, followed by an ulcer that forms within 48 hours and that canalso result in the exposure of bone surfaces.
a. Management
Wash with a non-irritant disinfecting agent, followed by application of ointment, and then administeragents such as antibiotics and anti-inflammatory drugs.
b. Preventative measures
Take great care to avoid an overdose of local anesthetic agents or application of excess pressure at the
point of insertion.
5

II. Psychosedation
Recently, concomitant psychosedation has been used more often in association with implant treatments.
It has been developed to enhance patient comfort and ease dental treatment by relieving the patient's
tension during the procedure. The methods used are currently classified into inhalational sedation andintravenous sedation, based on the different induction routes. The distinction from general anesthesia isthat the latter acts on the central nervous system (CNS) as a profound depressant that manifests as
unconsciousness, analgesia, muscular relaxation, and altered autonomic reflexes, respiration andcirculation. With psychosedation, on the other hand, patients retain consciousness and their protective
mechanisms and reflexes; however, with implant treatment, which is associated with substantial pain,use of local anesthetics is also a requirement 6). During implant surgery in recent years there has been arise in the number of procedures that are associated with the use of methods of deep sedation, which has
a strong suppressant effect on consciousness, breathing and circulation. This method requires control ofbreathing with airway maintenance. During dental surgery, where surgical and respiratory control areboth necessary, the use of conscious sedation is recommended, as the risks are lower and the patient does
not lose consciousness.

A. Inhalation sedation with nitrous oxide
1. Advantages and disadvantages
This intervention is very safe, with a fast recovery rate and no significant effects on breathing or thecirculation. A disadvantage is that its sedative effect can be influenced by conversation and mouth
breathing, and therefore can vary. Furthermore, the route of administration is via the nasal passage witha nasal mask, and therefore administration can be difficult in patients with nasal congestion, and themask can interfere with the surgical procedure. The fact that the surgical area is full of nitrous oxide canalso be a disadvantage.
2. Medication used, route of induction and dosages
Nitrous oxide is usually administered at a concentration of 30%, mixed with oxygen. It is a clear, tasteless,and non-irritant gas at room temperature and at atmospheric pressure. It is denser than air, and is moresoluble in water than oxygen or nitrogen. It is not flammable in itself but, in a similar way to oxygen, it
acts as an aid to combustion 7). Its rapid onset of action and rapid awakening, with no significant
influence on the respiration or circulatory systems, absence of muscle relaxation, and lack of apparent
hepatotoxicity and nephrotoxicity, makes it a safe agent for use as a sedative. However, neuropathy thatis symptomatically similar to vitamin B12 deficiency has been reported, therefore, management andawareness of operating room exposure to waste nitrous oxide is required.
3. Indications/contraindications
Use of this agent is indicated in patients with psychological stress such as marked anxiety with, and fearof dental treatment, or in cases where the procedure is complicated and requires either a long duration oftime or where surgery is very invasive. It is also effective in the patients who have systemic disorders
such as hypertension or other cardiovascular diseases that affect the whole body and are exacerbated bystress; and in those where past dental trauma occurred during treatments that resulted in harm or loss of
consciousness. The concomitant induction of local anesthesia is required in invasive surgical proceduresthat are often associated with strong pain, such as implant surgery or tooth extraction 8).
6

On the other hand, administration of nitrous oxide is contra-indicated in early pregnancy, in
intellectually impaired patients with whom conversation is difficult, and in those that havedifficulty

breathing through a nasal mask due to nasal congestion. Further contraindications are conditions where
air is trapped within the body, including otitis media, pneumothorax, bulla, and pneumoperitoneum, asinternal pressure in a closed, gas-filled cavity can rise with the inhalation of nitrous oxide. There havealso been cases where the interaction between a medical gas that has been used in eye treatment andnitrous oxide has resulted in deterioration in eyesight with a rise in intra-ocular pressure. This risk canbe anticipated based on the initial consultation, and should be considered a contraindication 9).
4. Equipment used for inhalational sedation
In order to establish continuous outflow of nitrous oxide/oxygen, a continuous flow-type inhaler technique
is employed, that uses a “reservoir bag” to accumulate the gas in the bag, and aid the inhalation of nitrous
oxide/oxygen by the patient. The ratio of nitrous oxide to oxygen can be decided with a mixing ratio
adjustment dial. The machine has been designed with a stopper that limits the concentration of thenitrous oxide to 30%, therefore, in cases where concentrations higher than this are necessary, the stopper
has to be lifted to enable the use of highly concentrated formulations 10). (Fig. 3-4-1)

Fig. 3-4-1
Inhalation sedation device for nitrous oxide

5. Perioperative control
a. Preoperative preparation
During the consultation period, necessary patient information such as the current and past history andcurrent medication use should be obtained. Contact the general practitioner for the specifics of any
physical conditions if necessary. Obtain baseline vital signs such as the blood pressure, heart rate, andrespiration rate. As patient cooperation is essential, the symptoms that occur at the time of nitrous oxide
administration must be explained, and the clinician must ensure that the patient fully understands andconsents to the procedure. In addition, the patient must be informed of the likely symptoms present whenan optimal level of sedation is achieved (refer to the next section). There are no fasting requirements,
however, to prevent vomiting, surgery should be avoided straight after eating (on a full stomach). In
addition, advise the patient to get enough sleep and to be physically prepared for the day of operation 11).
b. Level of optimal sedation(1) Maintenance of consciousness(2) Gain patient cooperation for treatment(3) The vital signs (respiration rate, blood pressure and heart rate) must be stable.
With nitrous oxide inhalational sedation, a feeling of warmth is noted, starting in the hands and feet and7then involving the whole body; subjects feel no pain, and become euphoric and relaxed. Different
individuals vary in their sensitivity to nitrous oxide, and the following symptoms indicate an excessive
concentration of nitrous oxide: loss of ability to open the mouth, complaints of discomfort, nausea,
excitation and becoming uncooperative 11).
c. Intra-operative management(1) Position and placement of monitoring equipment
Sit the patient in a reclining or dorsal position, in a position of comfort. Then attach asphygmomanometer and a pulse oximeter (SpO2) to measure and record the patient's initial bloodpressure, pulse, respiration rate and SpO2. Repeat this every five minutes after starting the nitrous oxide
inhalation.
(2) Nasal mask equipment, and confirmation of nasal respiration
Fit the nasal mask so that there is no leakage of the inhalation gas. Check that the patient is breathing
through the nasal passages by allowing inhalation of either air or 100% oxygen (Fig. 3-4-2).

Fig.3-4-2
Inhalation scene(3) Determining the flow rate
The total flow rate of the combination of nitrous oxide and oxygen should be set to be greater than thepatient’s respiratory minute volume. The respiratory minute volume of a grown adult is roughly six toseven liters per minute. To be more precise, it is the product of the tidal volume (approx. 10 ml/kg) and therespiration rate (approx. 12 / min) 11). Adjust the flow rate according to the ease of nasal respiration in thepatient.
(4) Inhalation and maintenance of nitrous oxide
Use an initial concentration of nitrous oxide of 10%. While carefully observing the patient, increase theconcentration in 5% increments to arrive at a concentration that provides optimal sedation.

The optimal

concentration of nitrous oxide differs for every patient but it is usually about 30%. Roughly 10 minutes isrequired to arrive at an optimal state of sedation. Mouth-opening during surgery can inhibit nasal
delivery of nitrous oxide; the patient’s nasal respiration should thus be monitored by observing the
movement of the reservoir bag, and the exhalation valve of the nasal mask. If the patient complains ofpain, maintain the concentration of nitrous oxide and add local anesthesia to relieve the pain. If he/she
complains of discomfort, loses consciousness, or becomes excitable or uncooperative, an immediate
reduction in the concentration of nitrous oxide is required 11).
(5) Terminating treatment
At the end of the surgical procedure, stop the nitrous oxide inhalation, and allow 100% oxygen to beinhaled.
d. Postoperative management8After inhalation of oxygen, leave the patient in a seated position for 5 minutes, and monitor their level ofconsciousness, blood pressure, heart rate and respiratory rate. If no abnormality is observed, they shouldsit quietly in the waiting room for over 10 minutes. Having confirmed that the patient is fully conscious,with no abnormalities in their vital signs, and that they can walk in a straight line, the patient can bepermitted to go home.
6. Common complications and their treatment
Long-term inhalation (continuous use for six days) has been reported to inhibit myelopoiesis andspermatocyte function, and can result in dependency. As a safety precaution, the nitrous oxide
concentration in confined spaces has been recommended to be kept below 25 ppm 10). As a result of thisrecommendation, preventative measures should be in place, including restriction of the duration of use(less than 8 hours/week), use of ventilation systems and opening of windows, use of a scavenging system
to collect expired gas from the patient, and sealing the nasal mask to prevent leakage of nitrous oxide.

B. Intravenous Sedation
1. Comparison with the nitrous oxide/oxygen inhalation techniqueThis method differs from the method described previously in that the drugs are administeredintravenously to achieve sedation. The advantages of this approach are that there is no effect on theability of the patient to communicate and that oral breathing is unimpaired. The effects are more
immediate and more predictable, and amnestic effects can be obtained. Furthermore, the equipment
required for inhalational sedation is not needed and there is no air pollution from the inhaled gas.
However, due to increased sedation with the administration of various pharmacological drugs, differencesin the speed of administration, and differences in the details of treatment and patients' systemic
conditions, loss of consciousness can occur, as well as suppression of respiration and circulatory
depression, a condition commonly referred to as “deep sedation”. Therefore this technique should only be
used by those who have a thorough knowledge of the techniques of anesthesia.
2. Medication used, route of induction and dosages (Table 3-4-2)
The main pharmacological agents used for intravenous sedation are: benzodiazepines (diazepam,
flunitrazepam, and midazolam) and intravenous anesthetics (propofol). (Refer to the clinical edition for
details).
3. Indications/contraindications
As for nitrous oxide inhalational sedation, this technique is applicable in all dental treatments. In
contrast to nitrous oxide-based inhalational sedation, however, there are no sedative effects on
conversation or oral respiration, and in cases where reliable sedation and an amnestic effect areimportant, this method should therefore be chosen. This method is particularly effective in procedures
such as implant treatments and wisdom tooth extraction where it is performed in association with local
anesthesia, where the surgery is relatively invasive, and during surgery that takes a long period of time.
In addition, patients who are very anxious or are afraid of dental treatments, or those who have in thepast become unwell or had impaired consciousness during treatment, should undergo this form of
sedation.
9

Benzodiazepine

Brand name

Intravenous anesthetics

DiazepamFlunitrazepam

Midazolam

PropofolSelsyn Horizon

Rohypnol
SileceDormicum

DiprivanPropofolIntermittent
Intermittent
Intermittent
administration.
administration.
administration.
Additional
Additional
Additional
Administration method
administration should administration should administration should
be a third to a half of be a third to a half of be a third to a half of
the initial dose.
the initial dose.
the initial dose.

Standard of sedative dos

Rate of administration

0.2-0.4 mg/kg

0.010-0.015 mg/kg

0.05-0.075 mg/kg

1-2 mg/30 seconds 0.1-0.2 mg/30 seconds 0.5-1 mg/30 seconds

Strandard of
maximum dose

20 mg

Dilution method

Improper

1 mg

5-7 mgTotal dose of 1A (2Total dose of 1A (10mg)mg)
Dilute to 12ml or 20ml
Dilute to 10ml

Intermittent
administration
Continuous
medication withsyringe pump
Introduction amount
0.3-1 mg/kg
Maintenance dose 2-3
mg/kg/hr

Ajustable

Depends on
sedation time

Improper(Risk of bacterial
infection)

Angilalgia hurts.
Sedactive effect is
Dosage and rate ofstrong.
When rate ofPossibility of angialgia
Important points
administration leads to
Respiratory
administration is fast,andduring induction anddepression by dosage
respiratory depression
respiratory depression
maintenancephlebitisand loss ofand rate ofadministration
consciousness
Anxiolytic andamnestic effects

StrongStrongStrongWeak

Awakening

Possibility of delay

A little slow

Relatively fast

Very fast

Chracteristic

Less
respiratory depression

Effects for mental
retardation
and autism

Suitable for
Has variety of regulation
short time treatment

Risk of resedationin after 6-8 hours

Using other drugs
toghetherleads to delay
awaking. Consider
hospitalization

Possibility of delaying Possibility of delaying
psychomotor
recovery of subjective
impairment
findings

Postoperative
considerations

Table 3-4-2 Properties of the typical pharmacological agents used in intravenous sedation
10

This technique is contraindicated in early pregnancy, where micrognathia causes difficulty inmaintaining an open airway, and with obesity, obstructive sleep apnea, and in patients who have aserious systemic disorder that should be treated prior to dental treatment. However, in the cases where
local anesthesia is inadequate for sedation, another option needs to be considered. Use of benzodiazepines
is contraindicated in patients suffering from medical conditions such as acute angle closure glaucoma andmyasthenia gravis, and alternative agents should therefore be used for these patients. It is difficult todetermine the level of sedation in infants, who are less inclined to cooperate with intravenous techniques;great care is therefore required.
4. List of apparatus and monitoring equipment
Prepare the pharmacological agent, a syringe (10-20 ml), an injection needle (21-22G), a tourniquet,
alcohol swabs, a butterfly needle, an indwelling venous cannula (20-22G), a fluid infusion, a drip infusion
circuit, an extension tube, a three-way stopcock, bandages, and a syringe pump.
For monitoring, prepare the sphygmomanometer, pulse oximeter and electrocardiogram.
5. Implementation methods
The practitioner and medical institutions should be fully aware of the following in using the intravenous
sedation technique 12).
First, before surgery, a pre-operative medical examination is necessary with a general health evaluation
and assessment of the risks. Checking whether the patient has eaten, and proceeding in accordance withthe concept of informed consent are essential. During surgical procedures, the following skills are
required: the ability to obtain intravenous access, assessment of vital signs, familiarity with setting up
and operation of the monitoring equipment, sufficient knowledge of the pharmacologically active
components of the sedatives and emergency medicines, technical ability to secure the airway during an
emergency, and preparation of equipment and drugs should an emergency arise.
Post-operative management requires an explanation of the evaluation criteria for discharge,
understanding of systemic symptoms that arise as sedation wears off, and the ability to identify and treat
complications should they arise.
6. Preoperative managementa. Preoperative preparation
During the consultation period, the required patient information such as the current and past history anduse of any current medications should be acquired. Contact the general practitioner for the specifics ofany physical conditions, if necessary. Obtain baseline values of blood pressure, heart rate, respiration rate,
body weight, and obtain patient consent, after explaining the need for sedation, and intravenous sedation
methods. The patient should be advised to avoid taking solids before surgery, and should fast for two to
three hours prior to the procedure. After surgery, the patient should not drive a vehicle, engage in any
intensive work, or make important decisions. Furthermore, in the case of elderly patients, a family
member or a care giver should be present to support them after treatment 8), 13).
b. Level of optimal sedation
The optimal level of sedation for intravenous sedation differs among individuals depending on the drug
11

used, in addition to variation in the rate of induction, even with the same agent, and the sedated state
may also vary between individuals. It is therefore important to monitor the patient’s response and vital
signs in order to achieve adequate, gradual induction of sedation with the use of sedative agents 11). The
general features of optimal sedation are: anxiety and tension are eased but consciousness is retained; thepatient becomes relaxed, followed by drowsiness, stabilization of blood pressure, heart rate, andrespiration rate; the patient follows instructions but with a delay in his/her response.
c. Intra-operative management(1) Placement of monitoring equipment
Seat

the

patients

comfortably,thenattachthe

sphygmomanometer,pulse

oximeter,andelectrocardiogram as necessary.
(2) Secure intravenous access and administer sedative agents
Wrap one arm in a sphygmomanometer cuff and insert the needle into a forearm vein. Choose a vein thatis thick and straight, and avoid tortuous or thin veins. Having established venous access, ensure that thearm position is fixed.
Measure baseline vital signs (blood pressure, heart rate and respiratory rate) and record these. If
diazepam or propofol is administered, the patient should be informed of the venous pain that occurs prior
to the drug being administered. The vital signs and the general condition of the patient should bemonitored and conversation maintained throughout the procedure. Stop the infusion if signs ofover-sedation are observed, even if the pre-planned dose has not yet been reached. These signs include
slowing of the speed of the patient’s verbal response, incoherent speech, and slight closure of the eyelids.
As a precaution, it is important to stop the patient from falling asleep, and gradual induction is necessary
while monitoring the state of the patient. Reduce the dose in elderly patients 11).
(3) Management during the procedure
Administration of local anesthesia can be started once the patient has reached his/her optimal sedationlevel, and the vital signs have been checked. During the treatment procedure, it is important to record
any changes in facial expression, verbal responsiveness, and vital signs (blood pressure, heart rate andrespiratory rate) every 5 minutes.
(4) A precautionary note
As the area of operation and the respiratory tract are in the same region, effective management of the
airway is essential. Pay particular attention when fitting a mouth gag, as it can result in airway
obstruction. Any pressure on the mandible or tongue exclusion by the surgeon or the assistant can also
lead to airway obstruction and dysphagia. Notify the surgeon, and raise the mandible if necessary. Any
pooling of blood, saliva, debris or liquid from washing should be avoided by adequate suction. Stop theprocedure if the patient starts coughing, and only continue once coughing has stopped.
d. Postoperative management(1) The end of the procedure
Termination of continuous infusion of propofol is dependent on the treatment and the level of sedation.
The termination period should be determined by evaluating the time to awaken taking the properties ofthe drug into consideration. Once the procedure is complete, check for the presence of any abnormalities,
including bleeding or inflammation in the oral cavity, and evaluate the level of consciousness, respiration,
blood pressure, and heart rate. If no abnormalities are observed, seat the patient on the bed or a sofa so12that they can rest. Leave the monitors as they were. Observe, in particular, for any recurrence of sedation,
vomiting, or bleeding 11).
(2) Criteria for discharging the patient
The basic criteria for determining the time of patient discharge are the vital signs and motor function,although the time is also dependent on patient’s physical condition, the duration of treatment, and thedrug used and dose administered.
As a guide to evaluate the vital signs, clear responsiveness, recovery of consciousness to the level present
before the operation, and normal respiration, blood pressure and heart rate should be present. On
assessment of motor function, the patient should not stagger and must be able to walk in a straight line,
and there must be sufficient recovery of muscle strength. Other tests include checking the patient's
ability to drink water, swallow, and urinate 12). Along with a means of transport and consideration of the
distance they will have to travel, and the presence of a supporting person, the decision to discharge thepatient should be made after taking all relevant factors into consideration.
(3) Important precautions for the patient
Caution the patient to avoid the following: driving vehicles, doing work that involves fine detail orimportant decision making, drinking alcohol, and vigorous exercise. Advise them to call for help if thefollowing occur: fever, vomiting, bleeding, or pain at the site where local anesthetic was injected.

III. General anesthesia
A. Introduction to general anesthesia
In terms of elimination of surgical pain, both local anesthesia and general anesthesia appear similar.
With more invasive surgical techniques, the body's reaction increases commensurately, and an anesthetic
agent is therefore required to act on the central nervous system and suppress biological reactions. By
suppressing the central nervous system with general anesthesia, along with an analgesic effect, there isalso loss of consciousness; muscular relaxation; immobilization; and depression of respiration, thecirculation, and autonomic reflexes, and therefore effects on the whole body become important. These
effects do not occur simultaneously and appear in the following order: amnesia, loss of consciousness,muscular relaxation, analgesia, and impairment of autonomic reflexes, depending on the depth ofanesthesia. It thus becomes necessary to manage all aspects of bodily function.

B. Systemic management
1. Preoperative preparation and evaluation of the patient's condition
a. The patient's past history
Refer to the patient's medical records and note present and past medical conditions, any current
medications, family history, surgical details and results of clinical tests.
b. Medical examination
The dentist in charge of anesthesia should take note of any prior medical conditions, previous surgery,and any anesthetic exposure.
c. Evaluation of the patient's condition before surgery
Evaluate preoperative problems in order to determine the risks of anesthesia and the surgical procedure
for this patient by means of history-taking, visual examination (physique and appearance, jaw and neck,13

respiratory conditions, and the condition of the arms and legs), palpation, and auscultation, along withlaboratory results.
d. Explanation to the patient
Explain to the patient and their family the anesthetic methods that will be used, dietary restrictions andany pre-anesthetic medications.
e. Notes
Describe the anesthetic method along with surgical details, the state of the body, and how the airway will
be secured, including the discussion with the physician in charge
2. General anesthesia techniquesa. Pre-anesthetic medication
The aim of this medication is to relieve mental strain due to the prospect of surgery and anesthesia,
suppress saliva and airway secretions, restrict harmful reflexes, obtain analgesia and prevent conditions
such as aspiration pneumonitis. Recent advances in general anesthetic techniques and anesthetic agents
have reduced the need for pre-medication in some facilities, therefore, listing of different agents and thedetails of their pharmacological effects will be omitted here.
b. General anesthetics (refer to Chapter 5: Implant-related drugs, and the clinical edition for moredetails)(1) Inhalational agents
These are administered with assisted respiration in order to reach levels required for general anesthesia.
Often the combination of nitrous oxide, a gaseous anesthetic agent, and sevoflurane or isoflurane asvolatile anesthetic agents, are administered through assisted respiration.
(2) Intravenous agents
An intravenous infusion can be used to provide sedation. The main drugs in current use are barbital,
propofol, benzodiazepines, ketamine, and narcotics. These are often co-administered with inhalation
anesthesia.
(3) Alternative agents used for general anesthesia
A neuromuscular blocking agent such as vecuronium is used if relaxation of the muscles is necessary.
c. Options for securing the airway 14)(1) Endotracheal anesthesia
The surgical area and airway are in the same region, therefore, general anesthesia in dental surgery
often uses endotracheal intubation that involves inserting a tube through the trachea in order to secure
the airway. The different routes of insertion can be divided into, oral, nasal and via the trachea(tracheotomy).
(2) Mask anesthesia
A face mask cannot be used in the field of dental surgery, as it covers the area of surgery. The use oflaryngeal masks for general anesthesia in selected cases has recently become prevalent.
d. Inpatient or outpatient
Generally, patients come in on the day before the surgery, and leave after a few days. With recent
developments in the agents and methods used for anesthesia, it has become possible to come in on the dayof surgery and leave, after fully awakening, and if there are no problems. This way, dental surgical14

patients can be treated as outpatients.
3. Intra-operative management
a. Respiratory management
The aim of respiratory management is to supply sufficient oxygen to the lungs and eliminate excessive
carbon dioxide produced during metabolism by ensuring appropriate ventilation. Ventilation should bemaintained through the use of endotracheal intubation and assisted ventilation to overcome the loss of
consciousness, loss of the airway and suppression of respiration that are effects of general anesthetics.
b. Circulatory management
It is vital to maintain adequate circulatory function with an acceptable heart rate and blood pressure inorder to transport oxygen, carbon dioxide, hormones, and other components vital for the maintenance oflife. It is essential to maintain the blood pressure and heart rate by stabilizing the autonomic nervous
system and preserving the circulating blood volume.
c. Metabolic management
To enable sufficient anaerobic respiration at a cellular level, it is essential to maintain the basics of
acid-base equilibrium, fluid and electrolyte balance, and body temperature .
d. Observation of vital signs and monitoring
For patient surveillance, monitoring during general anesthesia and surgery should include respiration,
circulation and metabolism.
(1) Respiration
Respiration rate, tidal volume, pulmonary auscultation, fraction of inspired oxygen, pulse oximetry(SpO2), blood gas analysis, end-tidal carbon dioxide monitoring, etc.
(2) Circulation
Cardiac sounds, heart rate, blood pressure, arterial pressure, the electrocardiogram, central venous
pressure, etc.
(3) Metabolism
Body temperature, blood sugar level, urinary sugar, urine ketones, acid-base equilibrium etc.
(4) Central nervous system
Electroencephalography, Bispectral index (BIS)(5) Others
Urinary output, muscular relaxation, anesthetic gas concentration, etc.
e. Notes
The area where dental surgery is performed is rich in blood vessels and, in addition, general anesthesia
results in a vasodilatory effect. Consequently, copious bleeding is often encountered. Dental anesthetics
that contain vasoconstrictors are often used in anticipation of bleeding during surgery. By using local
anesthesia, the dose of general anesthesia can be reduced, with the additional benefits of decreased
bleeding and less sedation after surgery. For these reasons, the concomitant use of local and generalanesthetics is often seen in dental surgery 14).
4. Postoperative managementa. Prevention of postoperative complications15

Support the whole body based on monitoring of factors such as the level of consciousness, respiration,
heart rate, blood pressure, body temperature and urinary output. Patient monitoring devices that should
be prepared include a sphygmomanometer, electrocardiography, a pulse oximeter, as well as an oxygen
supply, and suction, emergency medications and an emergency cart (containing emergency medical
devices and drugs).
The main postoperative complications are: respiratory depression, airway obstruction, hypertension,
hypotension, arrhythmia, delayed awakening, agitation, shivering, seizures, fever, hypothermia, retching,vomiting, hepatic dysfunction and renal dysfunction.
b. Pain management
Postoperative pain control not only relieves pain but also prevents postoperative complications. It is
common to administer non-steroidal analgesics (suppository and intramuscular/ intravenous injection).

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Kaneko Y. Local anesthesia in dentistry Q&A. Osaka. Shinryoshinsha Co., Ltd. 2004; 112-113. (inJapanese)5)

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